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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: iSCSI: response to second login (with same ISID)> I'd vote for (2) for the following reasons : > > a) It is possible for initiators to use the ISID as a scheme to > establish persistence of their O.S. device files. In doing so, > initiators would attempt to obtain the same ISID for a given > session to > a given target ports across boots. (and rightly so, for > enabling targets > to track persistent reservation like properties, etc). > > In the event where the initiator went through a non-orderly shutdown > which did not close all sessions, it would attempt to re-login on > re-boot with the same ISID. If the target rejected this re-login, per > (1) (citing an invalid ISID), the initiator would no longer be able to > maintain persistence of the session to an ISID. > > b) Using (2) allows the hosts to hint to the target that the previous > session is now stale and thus triggers clean-up of stale session > resources. This seems to me to provide another example why ISID should *not* be used for persistent reservation re-establishment. It's ambiguous whether this is a case of "defective initiator" or "initiator trying to re-claim persistent reservations" and there is no way for iSCSI to resolve this question. Since persistent reservations are SCSI layer things, lets try to find a way to keep their implementation from forcing unnecessary limitations at the iSCSI layer. The use of init. name+ISID+target name for identifying persistent reservations needs further discussion before we allow it to creep into iSCSI protocol rules. I've very uncomfortable with treating ISID like a fixed address just because SCSI persistent reservations don't have a sufficient SCSI layer mechanism. Seems like this will force all kinds of layering violations into iSCSI. Marj
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